Key Financial Data Of Group
| Concept | 2023-04-01 to 2023-12-31 | As at 2023-12-31 | 2023-10-01 to 2023-12-31 | As at 2023-03-31 | 2022-04-01 to 2023-03-31 | As at 2022-12-31 | 2022-04-01 to 2022-12-31 | 2022-10-01 to 2022-12-31 | 
|---|---|---|---|---|---|---|---|---|
| Key financial data of group | ||||||||
| Business results of group | ||||||||
| Net sales | 
                                                2,292,669,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,322,112,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,579,826,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | 
                                                264,215,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                28,814,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -58,493,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) attributable to owners of parent | 
                                                221,998,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                22,569,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -60,210,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Comprehensive income | 
                                                219,625,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                28,777,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -55,594,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets | — | 
                                                3,343,485,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                3,124,151,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                3,039,888,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Total assets | — | 
                                                3,893,835,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                3,842,109,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                3,557,274,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Basic earnings (loss) per share | 
                                                70.58
                                                
                                             | — | 
                                                32.10
                                                
                                             | — | 
                                                7.17
                                                
                                             | — | 
                                                -19.13
                                                
                                             | 
                                                11.20
                                                
                                             | 
| Diluted earnings per share |  | — | — | — |  | — |  | — | 
| Equity-to-asset ratio | — | 
                                                0.859
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.813
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.855
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — |